Thesis (Ph. D.)--University of Alabama at Birmingham, 2008. / Title from first page of PDF file (viewed Feb. 13, 2009). Includes bibliographical references.

Thesis (M.A.)--University of Texas at El Paso, 2009. / Title from title screen. Vita. CD-ROM. Includes bibliographical references. Also available online.

Thesis--University of Oklahoma. / Bibliography: leaves 154-165.

Doctor of Philosophy / Department of Statistics / Christopher Vahl / Veterinary drugs are used extensively for disease prevention and treatment in food producing animals. The residues of these drugs and their metabolites can pose risks for human health. Therefore, a withdrawal time is established to ensure consumer safety so that tissue, milk or eggs from treated animals cannot be harvested for human consumption until enough time has elapsed for the residue levels to decrease to safe concentrations. Part of the process to establish a withdrawal time involves a linear regression to model drug residue depletion over time. This regression model is used to calculate a one-sided, upper tolerance limit for the amount of drug residue remaining in target tissue as a function of time. The withdrawal period is then determined by finding the smallest time so that the upper tolerance limit falls below the maximum residue limit. Observations with measured residue levels at or below the limit of quantitation (LOQ) of the analytical method present a special challenge in the estimation of the tolerance limit. Because values observed below the LOQ are thought to be unreliable, they add in an additional source of uncertainty and, if dealt with improperly or ignored, can introduce bias in the estimation of the withdrawal time. The U.S. Food and Drug Administration (FDA) suggests excluding such data while the European Medicine Agency (EMA) recommends replacing observations below the LOQ with a fixed number, specifically half the value of the LOQ. However, observations below LOQ are technically left censored and these methods are do not effectively address this fact. As an alternative, a regression method accounting for left-censoring is proposed and implemented in order to adequately model residue depletion over time. Furthermore, a method based on generalized (or fiducial) inference is developed to compute a tolerance limit with results from the proposed regression method. A simulation study is then conducted to compare the proposed withdrawal time calculation procedure to the current FDA and EMA approaches. Finally, the proposed procedures are applied to real experimental data.

This diploma thesis deals with aspects of breaking the habit of smoking. My thesis consists of theoretical and practical part. The theoretical part is divided into three main chapters: smoking, impact of smoking and breaking of the smoking habit. I also defined the history of smoking, type of tobacco consuming, addiction to tobacco, treatments of the addiction, negative aspects of smoking etc. Practical part consists of quantitative research through questionnaires. The aim of my thesis was to find out what is tobacco addiction, gather the information and experience from the smokers who had experience with breaking their habit, analyze the methods of breaking the smoking habit and explain their main motivations for quitting the smoking. I have also included statistic data of my research.

Students experience stress due to many factors including educational unpreparedness, financial strain and the inability to integrate socially. This mixed methods study aimed to investigate stress levels of undergraduate students in a post-1992, Scottish university and the potential for measures of stress to act as an indicator of student withdrawal. Additionally, the project was concerned with students' use of support services and the development of a resource to facilitate student resilience with the aim to impact positively on retention. The level of perceived stress reported by students appeared to be high and was coupled with intention to dropout across all study levels. Students' psychological wellbeing appeared to be much lower than results published for the general population and actual withdrawal within the sampled cohort was higher than the University's formal figures would suggest. Perceived stress predicted a student's intention to withdraw but this association did not transfer to actual withdrawal suggesting that other factors, most likely coping mechanisms, play a part in mediating the withdrawal behaviour. Further data collection is required to confirm if a combination of perceived stress and coping data more accurately predicts actual withdrawal, however results showed that measures of perceived stress could be used to indicate a proportion of ‘at risk' students. Low use of avoidance and distraction coping was a better predictor of low self-reported stress than was high use of adaptive coping and this may have implications for interventions that endeavour to reduce stress through improved coping. Despite the seemingly high levels of stress and potential worry over dropout, students were reluctant to seek support and many were unaware of the support services available. An online, stress education resource was developed to build students' understanding of stress and the support available. It was envisaged that this would reduce stigma, aid in student self-awareness and self-assessment and improve their coping repertoire. The intervention was trialled alongside controls and results demonstrate that further work needs to be done to embed stress resilience into the student life cycle. The project reaffirms the need for concern over student wellbeing and highlights areas for improvement. Given students in this study may be considered ‘engaged', results bring to light a population, previously thought to be ‘low risk', but who could benefit from additional support to prevent unnecessary underachievement or attrition.

O consumo de cafeína tornou-se popular em adolescentes devido ao aumento da ingestão de bebidas comercializadas na forma de bebidas energéticas. Alguns estudos consideram que os efeitos benéficos da cafeína são atribuídos a uma reversão dos sintomas de abstinência. Neste estudo, foram investigados os efeitos da administração crônica de cafeína em ratos desde a adolescência (40 dias de idade) até à idade adulta (3 meses de idade) na memória de reconhecimento e BDNF e proteínas relacionadas a sua sinalização nas regiões do córtex e hipocampo. A cafeína (0,3 e 1,0 g/L) foi administrada na água de beber durante o ciclo de ativo dos animais (ciclo escuro) e retirada durante os fins de semana. Este protocolo foi desenvolvido a fim de mimetizar o consumo humano. Para as experiências de privação (abstinência),a administração crônica foi interrompida 24 ou 48 h antes do teste de tarefa de reconhecimento de objetos. Na tarefa de reconhecimento de objetos, foi possível observar os efeitos positivos da cafeína sobre a memória de reconhecimento, pois os animais tiveram um bom desempenho na tarefa. Entretanto, mesmo após a interrupção do tratamento os animais continuaram desempenhando bem a tarefa, dessa forma a abstinência de um tratamento crônico com cafeína não influencia a memória de reconhecimento. A cafeína na sua dose mais alta (1,0 mg / mL) e 24 h após a retirada, causou uma diminuição nos níveis de BDNF no hipocampo e nenhum efeito sobre as proteínas proBDNF e TrkB. Em contrapartida, no córtex a cafeína em ambas as doses diminuui os níveis de BDNF, um efeito que persistiu apenas para a dose mais elevada em ambos os tempos de retirada. O ProBDNF teve seus níveis diminuídos pela cafeína (1,0 mg / mL) após 48 horas da retirada, enquanto a cafeína em ambos os tempos de retirada aumentou receptores TrkB. Como mencionado anteriormente, estes resultados mostraram que a cafeína administrada durante a adolescência até a idade adulta, seguida da sua retirada não afeta a memória de reconhecimento. Estes efeitos poderiam ser atribuídos ao desenvolvimento da tolerância por tratamento crónico. Além disso, o aumento de receptores de TrkB seguido por diminuição de BDNF pode ser contribuído para a ausência de efeitos de abstinência de cafeína na memória de reconhecimento. / The caffeine consumption has become popular among adolescents due to increased intake of beverages marketed as energy drinks. Some studies consider that the beneficial effects of caffeine are attributable to a reversal of withdrawal symptoms. This study investigated the effects cronic administration caffeine in rats since adolescent period (40 days old) until adulthood (3 months old) on recognition memory and BDNF-related proteins and their signalling in the regions of the cortex and hipocampus. Caffeine (0.3 and 1.0 g/L) was administered in drinking water during the light cycle and discontinued at weekends. This protocol was developed to mimic human consumption. For withdrawal experiments, cronic administration of caffeine was interrupted 24 or 48 h before the test session on object recognition task. In the task, we observed the positive effects of caffeine on recognition memory once that animals learned the task. However, even after treatment interuption animals continued performing the task, so the withdrawal of chronic treatment with caffeine has no effect on recognition memory. Caffeine at its highest dose (1.0 mg / mL) after 24 h and after removal, showed a decrease in BDNF levels in the hippocampus and no effect on protein proBDNF and its receptor TrkB. In contrast, in the cortex caffeine decreased BDNF levels at both doses, an effect which persisted for only the highest dose at both time of withdrawal. ProBDNF levels had decreased by caffeine (1.0 mg / mL) after 48 hours of removal, while the caffeine in both periods of increased withdrawal TrkB receptors. As mentioned earlier, these results showed that caffeine administered during adolescence to adulthood, followed by its removal does not affect recognition memory. These effects could be attributed to the development of tolerance for chronic treatment. Furthermore, the increase of TrkB receptors followed by a decrease in BDNF may be contributed to the absence of withdrawal effects of caffeine in recognition memory.

Introdução: Variações das condições ambientais no período neonatal alteram a fisiologia e o desenvolvimento de diferentes sistemas. Modelos animais de estimulação neonatal induzem alterações neuroendócrinas e comportamentais persistentes. O objetivo deste trabalho foi estudar os efeitos da manipulação neonatal sobre o consumo de dieta palatável em diferentes períodos de exposição a esse tipo de alimento na vida adulta, e seus desfechos em resposta à abstinência ao alimento palatável. Métodos: No dia 0 de vida (dia de nascimento), as ninhadas foram divididas em manipuladas (M) e não manipuladas (NM), as que sofriam manipulação neonatal foram separadas das mães e colocadas em uma incubadora por 10 min/dia (do dia 1 ao dia 10 de vida). Aos 21 dias foi realizada a sexagem, apenas as fêmeas foram utilizadas neste trabalho. Entre os 80 e 100 dias de vida foram pesadas e randomizadas e o trabalho foi divido em: Experimento 1– exposição crônica à dieta palatável – comparação entre 15 dias e 30 dias de consumo da dieta e Experimento 2 – abstinência da dieta palatável – comparação de 24 horas e 7 dias de privação do alimento palatável com animais sem abstinência. A dieta foi oferecida a partir dos 90 dias de vida (todas as ratas tinham no mínimo 90 dias de vida). Foram avaliados: peso corporal, consumo alimentar, depósito de gordura abdominal (antes e depois da abstinência) e os níveis de corticosterona, de TH e p-CREB na amígdala após abstinência. As análises entre os grupos foram realizadas usando diferentes modelos estatísticos, ANOVA de duas vias, ANOVA de medidas repetidas seguidas pelo teste post-hoc de Tukey e o Teste t de Student. Resultados: Experimento 1 – Ambos os 15 e 30 dias de exposição crônica à dieta palatável induzem efeitos metabólicos semelhantes. Experimento 2- As ratas manipulados no período neonatal mostram uma resposta peculiar à abstinência do alimento palatável após a exposição crônica dessa dieta por 15 dias, menor ingestão de alimento palatável após a retirada por 24 horas, acompanhado pelo aumento de TH e pCREB na amígdala. Conclusões: Este estudo sugere que as variações no ambiente neonatal podem afetar a resposta a abstinência aguda de dieta palatável, principalmente em um nível neuroquímico, aumentando o TH e presença de p-CREB na amígdala de indivíduos que sofreram manipulação neonatal e restrição de dieta palatável por 24 horas. / Introduction: Variations in environmental conditions in the neonatal period change the physiology and development of different systems. Animal models of neonatal stimulation induce neuroendocrine alterations and persistent behaviors. The objective of this research was to study the effects of neonatal handling on the consumption of palatable diet in different period of exposure to this type of food in adult life, and its outcome as a response to withdrawal to palatable food. Methods: On the day 0 of life (birth date), the offspring was divided into handled (H) and not handled (NH), the ones which underwent neonatal handling were separated from their mothers and put into an incubator for 10min/day (from day 1 to day 10 of life). By the age of 21 days a sexing was realized, only females were used in this research. Between the 80 and 100 days of life they were weighted and randomized and the study was divided into: Experiment 1- chronic exposure to palatable diet – comparison between 15 days and 30 days of diet consumption and Experiment 2 – withdrawal from palatable diet – comparison of 24 hours and 7 days of deprivation of palatable food on animals without withdrawal. The diet was offered from the 90th day of life on (all rats were at least 90 days of life). The following were evaluated: body weight, food consumption, abdominal fat deposit (before and after withdrawal) and the levels of corticosterone, TH and p-CREB of the amygdala after withdrawal. The analysis among the groups were carried out based on different statistic models, two-way ANOVA, repeated measures ANOVA followed by the Tukey post-hoc test and the Student’s t-test. Results: Experiment 1- both 15 and 30 days of chronic exposure to palatable food induce comparable metabolic effects. Experiment 2 –rats handled during the neonatal period show a peculiar response to palatable food withdrawal after chronic exposure to this diet for 15 days, ingesting less of this food after 24h withdrawal, accompanied by increased amygdala TH and pCREB. Conclusions: This study suggests that variations in the neonatal environment may affect the response to acute withdrawal from palatable diet, mainly at a neurochemical level, increasing the TH and p-CREB presence in the amygdala of neonatally handled individuals that suffered such restriction for 24 hours of palatable food.

abstract: To explore subtypes of social withdrawal in different sociocultural contexts, concurrent social, school, and academic correlates of shyness and unsociability were examined in 93 urban (Mage = 14.05, SD = 0.86 years) and 136 rural (Mage = 14.39, SD = 0.69 years) seventh and eighth graders from Liaoning, China. Adolescents' shyness and unsociability were assessed with self-, peers’, and teachers’ reports. Peer-group relationships (acceptance, rejection, and exclusion) were obtained from peer nominations. Adolescents reported perceived friendship quality (positive friendship quality, conflict and betrayal) and school attitudes (school liking and avoidance). Teachers rated students' academic engagement and performance. Academic achievement (exam grades) also was obtained from school records. According to factor and correlational analyses, shyness and unsociability emerged as distinct, but positively related, constructs, within each informant. Cross-informant agreements on shyness and unsociability were low to moderate, especially between teachers' and self- or peers' reports. Urban-rural differences were expected in the associations of shyness, but not of unsociability, with the correlates, but the hypotheses were not supported with multiple-group (urban vs. rural) path models. In the combined (urban and rural) sample, shyness was associated with negative peer relationships, low friendship quality, and negative school attitudes (for self- but not peer-reported shyness), but was unrelated to academic correlates. Self-reported unsociability related negatively to positive friendship quality and positively to academic achievement, but was unrelated to other adjustment correlates. Peer-reported unsociability, however, was associated with negative peer relationships, less positive friendship quality, low school liking, low academic performance, and low academic achievement. The study was an initial step towards understanding subtypes of social withdrawal and adjustment correlates in various domains among Chinese adolescents living in different social contexts. The lack of urban-rural differences was not consistent with the contextual-development theory. Like their Western peers, shy Chinese adolescents were at risk for relational and school adjustment problems, but they did not have academic difficulties. Unsociable Chinese adolescents also tended to have poor adjustment at school, including relational problems with peers and friends, negative school attitudes, and academic difficulties, but only when they were perceived as unsociable by peers, rather than themselves. / Dissertation/Thesis / Doctoral Dissertation Family and Human Development 2016

Made available in DSpace on 2016-06-02T19:23:02Z (GMT). No. of bitstreams: 1 6776.pdf: 1764671 bytes, checksum: 0befe5018516a7acffe79be054e73ae7 (MD5) Previous issue date: 2014-07-07 / Universidade Federal de Minas Gerais / Adolescence marks a period of increased vulnerability to drug abuse. Early initiation of tobacco use is strictly associated with alcohol use and dependence in adolescence and adulthood. The present study aims to investigate: 1) changes in anxiogenic-like effects and on operant ethanol self-administration in adult rats exposed to nicotine during adolescence; 2) changes on pro-dynorphin (PDYN) gene expression in the nucleus accumbens (NAc) on late nicotine withdrawal and after ethanol self-administration; 3) which brain areas are activated on short or long-term nicotine withdrawal during adolescence. Our results showed that pre-exposure to nicotine during ten days (3mg/kg/day; s.c) in adolescent rats, did not change anxiogenic-like effects in the elevated plus maze, 15 days after the treatment cessation [postnatal day (PND) 52], progressive ratio (PND 75-79) and binge (PND 81-84) in the operant ethanol selfadministration protocol. However, animals pre-treated with nicotine displayed increased motivation to saccharin seeking. No changes were observed on gene expression of PDYN 15 days after chronic nicotine treatment cessation or 24 hours after the last binge session of ethanol self-administration. Concerning the areas involved on nicotine withdrawal, we observed that adolescent rats exposed to nicotine through the minipumps during 10 days (PND 28-37), showed enhanced Fos activation in the medial prefrontal cortex (mPFC) 3 days after nicotine treatment cessation (PND 40). The percentage of neuronal activation in this group was 22.03%, of those activated neurons, 28.5% were GABAergic and only 2.5% were glutamatergic neurons. Meanwhile, 15 days after the mini-pumps were removed, no difference was observed on Fos activation in the different brain areas analyzed. We concluded that: a) administration of nicotine during adolescence was not able to modify anxiety-like behaviors and ethanol seeking behavior in adulthood; b) late nicotine withdrawal did not change gene expression of PDYN in NAc, as well as, did not change Fos protein neuronal activation in the regions of mPFC, NAc and habenula; c) short-term nicotine withdrawal involves the activation of neural ensembles in the mPFC. / A adolescência é o período de maior vulnerabilidade ao abuso de drogas. O início precoce do uso de tabaco está significativamente associado ao abuso e dependência de etanol na adolescência e na vida adulta. O presente trabalho teve como objetivo investigar: 1) as alterações nos comportamentos relacionados a ansiedade e na autoadministração operante de etanol em ratos adultos expostos a nicotina durante a adolescência; 2) as alterações na expressão gênica da pró-dinorfina (PDYN) no núcleo acumbens (NAc) na abstinência tardia à nicotina e ao final da autoadministração de etanol; 3) quais as áreas encefálicas ativadas na abstinência, imediata e tardia, à nicotina durante a adolescência. Nossos resultados mostraram que a administração de nicotina durante 10 dias (3mg/kg/dia; s.c), em ratos adolescentes [dia pós-natal (DPN) 28-37], não causou alterações nos comportamentos relacionados a ansiedade no labirinto em cruz elevado 15 dias após a término do tratamento (DPN 52), assim como não alterou a autoadministração operante de etanol na razão progressiva (DPN 75-79) e no binge (DPN 81-84). Contudo, animais pré-tratados com nicotina apresentaram aumento da motivação para a busca de sacarina. Não foram observadas alterações na expressão gênica de PDYN 15 dias após a suspensão do tratamento crônico com nicotina ou 24 horas após a última sessão do binge de etanol. Quanto às áreas envolvidas na abstinência à nicotina, observamos que ratos adolescentes expostos à nicotina, por meio de mini-bombas, durante 10 dias (DPN 28-37), apresentaram maior ativação de Fos no córtex pré-frontal medial (CPFm) 3 dias após o término do tratamento. A porcentagem de ativação neuronal nesse grupo, foi de 22,03%, sendo que 28,5% desses neurônios ativados eram GABAérgicos e apenas 2,5% eram glutamatérgicos. Entretanto, 15 dias após a retirada das mini-bombas não houve diferença na ativação de Fos nas diferentes áreas encefálicas. Concluímos que: a) a administração de nicotina, durante a adolescência, não foi capaz de alterar os comportamentos relacionados a ansiedade e o comportamento de busca pelo etanol na idade adulta; b) a retirada tardia da nicotina não promoveu alterações na expressão gênica de PDYN no NAc, assim como não promoveu alterações na ativação neuronal da proteína Fos nas regiões do CPFm, NAc e habenula; c) a retirada da nicotina a curto prazo envolve a ativação de grupamentos neurais no CPFm.